GP 15 - Xtreme Version

The GP 15 from Baudis is considered one of the best performing semi-scale model in its class to date - so rumours in relevant online forums say.
You can imagine that I was well curious to find out if it can accomplish this pledge...
To go all out I ordered the GP15 from Windwings in Germany with the hardshell option (3 layers of 160 gr carbon), they call it the Xtreme version of this model.

 

 

 

 

 

 

Baudismodel is known for their sophisticated models and good build quality. With the GP 15 they have a semi-scale high performance glider in their portfolio. With a wingspan of 4,3 m it is still compact enough to fit well in mid-sized cars. Transport is often a problem with big models, hence some constructions above this size go nowadays for a split fuselage and a 3 or even 4 part wing. That's nice, but rather expensive. The GP 15 doesn't have this features, but isn't a bargain either. However, you get a fine-built, stable, aerodynamic well-engineered airframe with a good finish. Anyway - prices for high-tech models go up like crazy recently - and it seems that customers are still willing to pay (me too 😇).

The excellent and the not so good
There are a lot of good things to say about this model, and the online forums are full of that. I want to point out the light and stable fuselage with mesmerizing spars in the tail and the high aspect ratio wing which is built with a high torsional rigidity (what really matters when you want to go fast). What I truly like is the Baudis LDS-system, that are precisely milled aluminum clevis and rods. This system doesn't hide completely inside the control surfaces, rather leaps out a bit, benefiting in better leverage and stability. It is not easy to install at first, but works perfectly in the end.
Airfoils come from Dirk Pflug, a name you will frequently hear together with new top-notch gliders designs. The claim is, that the GP 15 basically performs like a state of the art F3B model with these airfoils and wing shape. Of course, you have a bigger fuselage, this adds some drag - but not really much...

Fit and finish is generally good, and the plane comes out of the box more or less ready for equipment installation. Some details though, are not well-thought-out in my opinion: The mounting of the elevator is a clumsy solution, and you will see a lot of people modifying this. Furthermore, the inside of the cockpit is not fitting well, and my model shows a lot of small bubbles in the molded instrument mushroom. And the sealing lips have some gaps - I have seen this job done better at much lower prices. However, it is complaining at a high level. In the end, these are minor things, but Baudis could and should make this product even better!

Another thing, I don't like: the CG goes significantly forward if you add the brass slugs in the wing roots. I mitigated this effect by installing ballast bars into the fuselage accurately into the CG, luckily you have tons of space for that!

Flight experience
Firstly I was surprised how easy you can go slow and circle in thermals with the GP 15 without ballast, just don't add too much downward trim at ailerons in thermal flight mode. A little bit more trim at flaps is mostly a good idea and works against tip stall. Speed and pull-through is excellent, and with full ballast the model holds the pace superbly good. The aerodynamic fine-tuning at every corner comes into account here. In theory, the winglets contribute to a better performance at low speed but compromises the longitudinal agility a bit. If you are bothered with these, you can order small tiplets from Baudis. Even a sleek fuselage is available, lookup for Baudis' GP Racer.

The start is a little bit thrilling with my setup and full ballast, but if you are an average man you can do it!😔 I chose an efficient, quiet and not so powerful motor setup purposely, so thrust is on the lower side, but enough for a decent climbing rate.

Landing is mediocrely easy with crow-flaps, of course you have considerable speed and weight. Braking is not as strong as I am used to, due to the overall weight and not too big flaps. So, flying on slopes with a short landing zone could be a challenge and needs extra attention. The maiden flight with my GP 15 took place at Hoamalm in Salzburg, where landing actually was no hassle at all. And after some routine adjustments, the GP 15 performs in the air just superb, and man, does it look nice.

Conclusion
Is it worth the money? Well, you have to decide for yourself... For me, the GP 15 surely is a highlight of my modeler career, and after building and flying dozens of different sailplanes, I have to admit, this is the overall "best" of them to date - but also the most expensive one.

***

Ratings for parts and construction
( + = good, o = average, - = bad)

Fuselage:
+ stiff and light
+ magnificent spars in the tail section
+ 2,4 Ghz friendly front
+ perfect surface and color, no visible defects in the coating
+ servo cover fits without rework
+ LDS for rudder
+ stiff aluminum pushrod for elevator
+ decals in good quality
+ big enough for different motor setups (FES, impeller, etc.), retractable landing gear, water ballast system etc.
+ preinstalled tube for vario (optional for additional charge)
o seam is ok, but fairly visible (black/white)
- pivot tube holder unlovely glued in rudder fin

Canopy & cockpit:
+ ready to install
+ perfect fit of canopy to fuselage
+ hidden opener with small, neat "key"
+ snug instrument cluster
o glue residue between glass and frame needs rework
o cockpit fits not very nicely inside the fuselage (can be fixed)
- a lot of bubbles on molded instrument mushroom 

Wing:
+ perfect surface
+ trailing edge thickness just right in my opinion
+ thin flap gaps
+ perfect fit of wings, winglets and wing joiner
+ torsional rigidity
+ durable (3 layers of 160 gr carbon)
+ servo covers fit without rework
+ precise recesses for fuselage-wing connectors (Multiplex)
- ballast position affects CG too much

Elevator:
+ perfect surface
o sealing lip has some gap
o glass-fiber wedge for angle of incidence correction needed
- clumsy mount for elevator and cover (can be fixed)
- connection of the two elevator rudders via 1,5 mm pin is prone to become unfirm

Accessories:
+ brilliant LDS system
+ servo frames with opposing bearings included
+ ballast included
+ high quality bags for wing, stab and fin

Other:
+ extensive manual for LDS installation online (Baudis)
+ setup hints online
+ shipping in well protected box
+ support and contact to Windwings

***

 

Space en masse... so no problems for a tidy setup. 👍
The battery is fastened on an easy (with one screw) to remove glass-fibre board.
So the battery has always exactly the same position in the model.
Adjusting the CG is straightforward too by opening the Velcro fastener and moving the battery.
I used a 3D printer and PLA filament for some parts of the build.

 

 

Elevator and rudder servos are positioned in the tail.
Nice: rudder linkage is the same brilliant LDS-system as for ailerons and flaps.
The pushrod for the elevator is well engineered, too.

Retrofit: possibility to add 630 grams of ballast in the fuselage near the CG.
Thus enhanced speed and agility around the longitudinal axis.
Standard ballast (brass slugs with 720 grams) fit into the roots of the wing.

Modified fastening for the elevator hood with a magnet...
Results in a cleaner look and a quicker assembly. 

Tail section and pivot tube for total energy compensation with the
MicroVario from SM-Modellbau.

Semi-scale look with a small tail wheel.

I ordered the winglets in Kawasaki green.

Some coloring on the wing with adhesive film. Not exactly the same
tint as the winglets - but well, who really cares... 😎

The 20x13 GM Scale prop folds sleekly around the fuselage in
combination with a special scale spinner.

It all adds up to a stunning looking sailplane.

But in essence, flight performance is what matters for any high-tech model airplane - isn't it?
The Baudis GP 15 didn't disappoint me in this field either.

***

Setup
GP 15 Xtreme version (hardshell, 3 layers of 160 gr carbon)

Battery: Hacker TopFuel 5s-5000 mAh
Motor: Leopard LC500 6pol 1450KV with Micro Edition 5:1N 4plus-Inject/T
Controller: Jeti Mezon 80 pro
Prop: 20x13 GM Scale
Spinner: Windwings special 43 mm / 6 mm

Servos:
Rudder: KST X10 Mini (HV)
Elevator: KST X10 Mini (HV)
Flaps: 2 x KST X10 (HV)
Ailerons: 2 x KST X10 (HV)

RC/electronics: Jeti Duplex R10 REX, SM MicroVario

Weight without ballast: 5.270 gr
Max. weight: 6.630 gr
Original ballast: 720 gr, brass slugs in wing roots
Additional ballast: 630 gr in fuselage

Wing load without ballast: 75 gr/dm²
Wing load with full ballast: 94 gr/dm² 

Wing span: 4,3 m
Length: 1,85 m
Wing area: 70.6 dm²

Model produced at baudismodel.com, acquired at windwings.de.